1. Field of the Invention
The present invention relates to a window covering and, more particularly, to a window blind that is expandable downward and retractable upward in a vertical direction without needing a lift cord.
2. Description of the Related Art
A conventional window covering, such as a Venetian blind, roman shade and the like, usually comprises a lift cord to expand or fold the window covering. However, the lift cord depends from a side of the window covering so that the lift cord is easily tangled with a child's neck, thereby causing danger to the child. In addition, the lift cord protrudes outwardly from the window covering, thereby decreasing the aesthetic quality of the window covering.
A conventional window blind without a lift cord comprises a retractable shading member, a headrail connected with the upper end of the shading member, a bottom rail connected with the lower end of the shading member. The headrail has a receiving recess which has a bottom provided with a plurality of cord holes. A cord winding controller and a fixing seat are mounted on two opposite sides of the receiving recess of the headrail. A movable seat is movably mounted in the receiving recess of the headrail and is disposed between the cord winding controller and the fixing seat. At least one connecting cord is extended through the cord holes of the headrail and the shading member and is secured on the bottom rail. Each of the fixing seat and the movable seat is provided with a plurality of guide members for winding and guiding movement of the connecting cord. The cord winding controller has an interior provided with a rotation disk and a torsion spring. The cord winding controller is provided with a driving cord which is connected with the movable seat. The driving cord links the connecting cord on the fixing seat and the movable seat. Thus, when the bottom rail is pushed upward or pulled downward, the connecting cord is loosened or tightened to drive the driving cord so as fold or expand the shading member. Thus, the connecting cord and the driving cord form a balanced state so that the user can expand or fold the shading member easily. However, the conventional window blind without a lift cord has a complicated construction and cannot be repaired easily and conveniently, thereby increasing the cost of fabrication and maintenance. In addition, the conventional window blind is not assembled easily and quickly. Further, the shading member is expanded and folded by driving of the movable seat and the cord winding controller, thereby easily producing noise during operation the movable seat and the cord winding controller. Further, when the driving cord is scrolled or unscrolled by the cord winding controller, the cord winding controller easily produces noise due to operation of the rotation disk and the torsion spring in the cord winding controller.
The closest prior art reference of which the applicant is aware was disclosed in U.S. Pat. No. 7,487,817.